This invention pertains to molded rubber goods made at least partially of a heat setting rubbery polymer which has been cured against an associated mold surface.
Many types of rubbery polymers when cured under heat and/or pressure against a mold surface (usually of metal), have a tendency to adhere at least partially to that mold surface unless a mold release agent, such as mica dust, is applied to the mold surface or rubber article prior to molding. EPDM-type polymers are typical of this group of rubbery polymers which, without the aid of a mold release agent, oftentimes will stick to the mold surface and also present a rather dull exterior surface appearance. This dull surface is believed to be attributable at least in part to the poor release from the mold surface, and/or to blooming of accelerators or other additives compounded into the EPDM stock. Hose articles, for instance, are generally considered more acceptable when the exterior surface is smooth and relatively shiny rather than dull or dusty as a result of blooming at the surface or because of the presence of residual amounts of mold release agent.
It is a primary object of the subject invention to provide an exterior surface for molded rubber articles which will release from an associated mold without the need for a separate mold release agent, without the need to wash or otherwise remove mold release agent from the molded article, and which will enhance the surface properties of the article by presenting a smoother, shinier surface with minimized tendency to bloom.